Finally figured it out. I went to the B&N site on my PC, archived every single book, moved them all back into the Library, and now they show up again. Seems the Nook App wasn't "seeing" the books on the server.
OK, here goes my extreme newbiness, but...I just recently got the Nook Color, am running CM7 on SD, have installed the Nook app. I have a free epub book sitting on the internal memory, but can't for the life of me figure out how to open it in the app. In the stock Nook, I can just go into my library & there it is.
Thanks for any help!
If it is in your B&N library, use your PC to visit the B&N site and try what I suggested above. If it is something you sideloaded, you can try to mount your Nook to your computer and either sideload it again or move it to your SD card where CM7 may be able to see it better.
My CM7 NC library would not reload. I tried reloading the ROM multiple times (clockworkmod sd method CM wiki) and it still would not reload. So, I restored to stock (CM7 wiki clockworkmod sd), signed in to B&N under stock to make sure it worked. It was all good. I then reflashed CM7 via same method, started up wifi, signed in to market and downloaded the nook app. Walah. it reloaded the library. Its the long way but I am happy with the results.
Looking back, I think I lost the ability to sync Nook app when I lost the wifi ability on CM7 NC. I would like to know others experiences. Back to CM7 Goodness!!